Ryan:  Looks like you have a Krag infantry rifle that was 'Sporterized' by shortening the barrel, adding a pistol grip, filling the rear-sight opening in the hand-guard, checkering the wood extensively, and adding a commercial #57 Lyman 'Peep-sight'.  Your Krag's value would be based on its utility to a Hunter/Shooter ($275-$350 - IMHO).  It would be interesting to see a photo of the muzzle area and front sight.  Your Lyman sight has a button you push to 'quick release' the slide from its base.  You should then be able to dismount the bolt.  The custom work was not done by the arsenal.